1. Field of the Invention
The present invention is generally in the field of semiconductors. More particularly, the invention is in the field of semiconductor substrates for integration of optical and electronic components.
2. Background Art
Different substrate requirements for optical components, such as waveguides, gratings, and modulators, and bulk silicon electronic devices, such as bipolar and Complementary-Metal-Oxide-Semiconductor (“CMOS”) devices, hinder the integration of optical components and bulk silicon electronics on a single substrate. For example, optical components can be optimized on a Silicon-On-Insulator (“SOI”) substrate having a thin silicon layer situated over a thicker buried oxide layer, which is in turn situated over bulk silicon. In a SOI substrate that is optimized for optical components, the thin silicon layer in the SOI substrate can have an exemplary thickness of a few thousand Angstroms. However, bulk silicon electronic devices, such as vertical bipolar transistors, require much thicker silicon, such as silicon having a thickness of hundreds of microns.
Optical components have been fabricated using Silicon-On-Saphire (“SOS”) technology, which takes advantage of a transparent saphire substrate. However, an undesirably high defectivity rate in SOS substrates currently reduces the feasibility of integrating optical components and bulk silicon electronics on a SOS substrate. Additionally, the cost of the SOS substrate is very high.
Thus, there is a need in the art for an effective method for integrating optical components and bulk silicon electronics on a single semiconductor substrate.